Chapter 84

Question 0

When a process variable has no method of sending information to the final control element, the system is know as:
A) an automatic system
B) an open loop system
C) a cascading system
D) a feedback system
E) a feed forward system

Answer 0

B) an open loop system

Question 1

A variable adjusted in order to maintain or achieve a desired value of another variable is termed the:
A) process variable
B) final variable
C) manipulated variable
D) controlled variable
E) transmitted variable

Answer 1

C) manipulated variable

Question 2

The apparatus that converts current signals to pneumatic and pneumatic to current signals is a:
A) diverted
B) inducer
C) inverter
D) transducer
E) transformer

Answer 2

D) transducer

Question 3

A device that converts the measurement of a sensing device into a signal is a:
A) controller
B) logic device
C) primary element
D) relay switch
E) transmitter

Answer 3

E) transmitter

Question 4

State the most common signal range for pneumatic instrument signals:

Answer 4

20 - 100 kPa

Question 5

List two types of electrical signals used in control systems, and give examples of where each might be used.

Answer 5

Voltage signals - used with switching devices such as scanners, low water fuel cutoff, etc
Current signals - used for analog instruments where signals must be sent over long distances

Question 6

One common example of a photoelectric transducer used on boilers is the_____ scanner.

Answer 6

Flame